At the present carboxylated latices are manufactured using three different types of polymerization processes. These accepted processes are batch, semi-continuous or semi-batch and continuous.
Each type of process has its unique characteristics and limitations. Although the basic chemistry of free radical emulsion polymerization is common, each process differs substantially, in that different reaction components and conditions are found in each. Different materials, variations in process conditions, the method and logistics of material addition all play a major role in affecting final product properties and these factors vary from process to process.
The process of U.S. Pat. No. 3,966,661 imparts certain undesirable properties to the latex, requires low critical micell concentrations (CMC) and anionic surfactants of only certain types at relatively high concentrations to maintain desired reaction speed and reaction conversions.
U.S. Pat. No. 4,272,426 discloses the preparation of carboxylated latex from conjugated dienes, monovinyl noncarboxylic comonomers, unsaturated carboxylic acids and at least one N-alkylolamide of an alpha betaethylenically unsaturated carboxylic acid. The polymerization reaction is carried out in two or more stages in which all of the monomeric components except the N-alkylolamide are polymerized to a conversion of 50 to 80 percent in the first stage, the reaction is continued in the second stage to which is supplied the balance or all of the N-alkylolamide. The process of U.S. Pat. No. 4,272,426 does not disclose or suggest the splitting of all of the monomeric components between two or more reactors in a continuous process, nor does it contemplate the properties that can be achieved when all of the monomeric components are divided between two or more reaction stages.
Not disclosed nor contemplated by the prior art the present invention overcomes the requirements of high surfactant and electrolyte concentrations and thereby achieves desired particle size distribution without latex particle agglomeration in an efficient and continuous process.